Well as I posted before the 300-6 Non Fuel Injected motor in my truck misses. At first I was told it was a vacuum leak. Well it seemed odd to me if it was that it only did it at certian RPMs. It does not do it at low rpms but at high rpms it is rather bad Well this late summer I was driving it and noticed when the motor got warm it dieseled when I shut it off. Well seems to me me that the engine is out of time. So would this contribute to the miss in the engine? I also should go through and put new plugs and wires it it. They don't cost that much.

TIA,
ORB

 

an out of time engine could easily shake... but if its higher rpm specific it sounds to me like somethings out of balance... any noise or just a little shake? if its a little shake and no noise it could be a u-joint going out or just tires out of balance

 

It ain't a U-joint as it does it standing still as well. More a noise then a shake. It doesn't appear to effect anything. (other than my frustration factor) Still it annoys the ____ out of me. Seems to be on one of the back cylinders either 5 or 6 ain't sure on that but I have a pretty good hunch.

 

check your pushrods .My dad had a 6 cyl. ford that bent them often.

 

Check for plug wires arcing to one another, all I-6's like to do this when the wires get old because the wires are so long and drape across one another.

Justin

 

Do a compressoin or better yet a leak down test

 

I checked into it. It will cost a whole $35 for new plugs and wires. Next time I'm in town I'll make a point to get a set.

Where I could I get a compression test done? I understand the concept of how it is done but I lack the tools to do it.

 

just go to your local walmart in the automotive section... theyve got a screw-in compression tester... use it as youre changing spark plugs... it costs around 25 dollars i think for the tool- and its a heck of a lot cheaper to buy the tool than pay someone to do it

 

If your compression is good, and everything else fails, run it hard and blow the carbon out of it. You'll know when it happens. There's not a chance you're going to over-rev this motor, not with the factory carburetor.

Dieseling often means there's a big buildup of carbon on the heads. There's a trick to tuning cars that can't be tuned that dates to the 50's & 60's, and this motor design qualifies. Some little old lady would putt-putt around in her big old Buick with a great big V8, and after a while, it just ran terrible. No mechanic could get it to run right. Carb rebuilds, ignition, plugs, the works. Nothing. What happened was the engine never got worked hard, never got nice and hot, because just off idle could get her around town just fine, and had all kinds of deposits in the heads. So back then, in this area, Rt 29 wasn't finished yet, but it was paved. Just miles and miles of fresh wide blacktop. What'd you'd do is make sure the brakes and tires were good, and you'd go for a drive late at night. You'd just start that speedometer climbing. Eventually you'd get to a speed where the engine would run poorly and wouldn't go any faster, usually above normal highway speed, maybe 70 or 80- it just couldn't perform under load. Misfire, stumble, detonate; you think you'd throw a rod. Then it would start to run real bad and blow big clouds of black smoke out the tailpipe. Just when you thought it was going to die, the engine would smooth out, sound strong and pick up speed. You'd take it back to Grandma or her mechanic, and they'd drop thier jaws because you fixed the car that couldn't be fixed.

Good luck, and watch out for cops.

 

Running a little water or ATF through the carb throat at high idle will do the same thing that bigblue suggested, without the risk of getting caught.

Justin

 

What happened to good old fashioned carb cleaner? I think it even says on the can that it helps loosen carbon deposits in the head / valves.

BAH! I'm too old fashioned.

The water thing sounds interesting, tho...

 

Once you get the crud out of the head, a periodic WOT run out of a toll booth or merge ramp is all you need to keep it clean. I go WOT on my truck 20-65mph (warm motor) about once every week or two of city driving. And it keeps your smile looking good, too.

 

Thanks guys. I'll start with new plugs and wires and go from there. The suggestion of working it hard by driving like H*** might not be the issue as I drive 70 on a regular basis

 

The easiest thing would be to pull your vacuum lines one by one and see if they hold vacuum. Do that and come back.

Vince